1. Field of the Invention
This invention relates to a display device such as a liquid crystal display having a back light for illuminating from behind.
2. Description of the Prior Art
A non-light emitting display device such as a liquid crystal display has a back light unit for illuminating from behind. The back light unit comprising, for example, a line-shaped light source such as a cold-cathode tube fluorescent light, a light guide plate for introducing light emitted by a light source through a side surface facing to the light guide plate and emitting the light from an emitting surface, a reflector for efficiently introducing light from the light source to the inside of the light guide plate by using reflecting surfaces which are surfaces around the light source except for a side surface facing to the light source, and a reflecting sheet for returning light escaping from a back surface of the light guide plate to the light guide plate again, which is provided on a back surface of the light guide plate. If necessary, a lens sheet for improving the brightness by condensing light emitted from the emitting surface within a visible angle, and a diffusing plate for leveling off the brightness are provided above the emitting surface. These elements are housed in a holder for forming an outward shape of a back light unit.
A liquid crystal display panel is housed in a metal frame which holds the liquid crystal display panel around a proximity of side surfaces and has an opening serving as a display area, and the display panel is combined with a back light unit. (See JP, 4-355428, A as one example.) For combining the back light unit and the liquid crystal display panel, a mechanism for engaging either of the holder or the frame with the other, or both of them are housed in an other holder forming an entire display device unit.
A sheet-shaped reflector of which an inner surface is generally a reflecting surface is arranged around the light source, and an end surface of the reflector is adhered and fixed to the light guide plate.
It is required to fix the reflector so as to correspond to the light guide plate, and it causes a large amount of time and labor. In addition, such a work demands considerable accuracy and prevents improvement of assembling workability, causing an increase in cost.
The sheet shaped reflector is difficult to retain a desired shape since it is easily deformed, although the sheet-shape reflector can be fixed to the light guide plate in proper condition. And a sufficient space between the light source and the reflector can not be secured. In a case that a sufficient space can not be secured, even though light radiated to a direction other than a side surface of the light guide plate (an incident surface), that is light radiated to upper and lower directions or behind of the light source, is reflected to the reflector, some of light may travel to the light source and can not be incident to the side surface of the light guide plate (an incident surface) efficiently. Then, when an amount of light incident to the light guide plate decreases because the light from the light source can not be incident efficiently. An amount of light emitted from the light guide plate also decreases and a desired brightness can not be obtained.
Some reflectors are formed with special hard materials which are not deformative, however, they also requires a large amount of time and labor, and considerable accuracy in mounting works as in a case of a sheet-shaped reflector. Therefore the workability is degraded, causing an increase in cost.
This invention was made to solve these problems. The invention has an objective to provide a display device in which a predetermined space between a light source and a surface other than a side surface of a light guide plate is secured so as to obtain sufficient brightness for illumination by efficiently utilizing light emitted from the light source. Furthermore, the display device according to the present invention does not require a work for fixing a reflector to a light guide plate so that the display device can improve assembling workability and accuracy and contribute to cost reduction.
A display device according to the present invention comprises a light source, a light guide plate for introducing light emitted by the light source to an incident surface on a side of the light guide plate and emitting the light from an emitting surface, a non-light emitting display device which is illuminated by light emitted from the light guide plate, and a holder for housing the light source, the light guide plate, and the non-light emitting display device. The holder includes a first holder having a back surface for covering at least a back surface of the light guide plate, a second holder having an opening corresponding to a display area of the non-light emitting display device and formed dividably from the first holder, and a light source housing chamber for housing the light source having an opening corresponding to the incident surface of the light guide plate is formed by combining the first and second holders.
The first holder includes a first housing area formed in a lower part of the light source housing chamber, and the second holder includes a second housing area formed in an upper part of the light source housing chamber.
In this invention, a holder for holding the entire display device is divided into two pieces, and a light source housing chamber for housing the light source is also divided, and thus a mounting work of the light source to the light source housing chamber is easy.
The first and second holders are formed with resin.
The holder, which is dividable, includes a flexible connecting part and the connecting part connects the divided holders.
In this structure, an assembling work is further easy.
A reflecting surface corresponding to a light emitting part of the light source is provided on an inner surface of the light source housing chamber.
Therefore, a separate reflector for introducing light emitted from the light source is unnecessary because the display device of this invention is provided with the reflecting surface corresponding to the light emitting part of the light source, and mounting work of the separate reflector is not necessary and the assembling workability can be improved.
The light source housing chamber may include a light source holding part for holding the light source.
The display device of this invention may include a shading piece facing to the emitting surface of the light guide plate in a periphery of an incident surface.
In the display device of this invention, a back surface of the first holder is formed to be a reflecting surface and a reflecting sheet is not provided between the light guide plate and the back surface.
In the display device of this invention, the back surface of the first holder is formed in a predetermined shape so as to control light reflection and diffusion.